[en] Radon-222 and Radon-220 and its short-lived decay products in the atmosphere are the most important contributors to human exposure from natural sources. Measurements of ²²²Rn and ²²⁰Rn and their progeny concentrations in indoor and outdoor environment are important to estimate the inhalation dose to the population of the region. Also, measurements of ²²²Rn and progeny concentrations in the atmosphere, soil gas and rate of exhalation have many environmental and geophysical applications. We have carried out extensive study on indoor and outdoor ²²²Rn, ²²⁰Rn and their progeny concentrations and their dependence on ambient temperature, pressure and humidity, rate of ²²²Rn exhalation rate from the soil and concentrations in soil gas in the West Coast region of India for the last 15 years. This paper presents a summary of the results of these studies

[en] The activities of ⁴⁰K, ²²⁶Ra, ²²⁸Ra, ²¹⁰Po, ²¹⁰Pb, ¹³⁷Cs and ⁹⁰Sr were determined in a number of natural samples in the environment of Mangalore, South India where large-scale industrial activities are envisaged. Well-established nuclear techniques were employed to measure the activities and wherever necessary radiochemical methods were also followed. The measurement of transfer coefficients indicated that the uptake of ²²⁶Ra, ²²⁸Ra and ²¹⁰Pb in paddy is higher than that in vegetables. The measured activity ratios of ²¹⁰Po:²¹⁰Pb and ²²⁸Ra:²²⁶Ra in soil samples suggest the existence of equilibrium between the corresponding radionuclides in normal background areas and disequilibrium in high background areas. The intake of radionuclides by the population and the internal dose were estimated. The annual internal effective dose for the population is found to be 341 μSν year^-1 which mainly arises from ⁴⁰K and ²¹⁰Pb. (author)

[en] Leaves, stem and bark samples from several plant species were collected from tropical forest of Kaiga, in the west coast of India where two nuclear power reactors of 220 MW each have just been commissioned and another two are under construction, and analysed for their ²²⁶Ra, ⁴⁰K and ⁷Be concentrations. The activities of ²²⁶Ra and ⁴⁰K in plants were found to vary in the range BDL-13.2 and 12.0-797.3 Bq kg^-1, respectively. Plant show significant ⁷Be activity in leaves, the activity varies in 72.5-1060.8 Bq kg^-1. Stem and bark of plants show higher levels of ²²⁶Ra and ⁴⁰K when compared to leaves. Soil-to-plant transfer factor for ²²⁶Ra and ⁴⁰K were found to vary in the range BDL-0.37 and 0.09-5.61, respectively for different plants. The concentration of ²²⁶Ra and ⁴⁰K in leaves depend on the age of the leaves

[en] Several soil and vegetation samples from the environment of Kaiga nuclear power plant site in the south western region of India were analysed for ²¹⁰Po. The vertical profile, particle-size distribution, seasonal variation and the dry deposition rate of ²¹⁰Po were measured employing the chemical method and α - counting technique. ²¹⁰Po activity in soil varies from 17.1 to 228.2 Bq kg^-1 with a mean value of 83.3 Bq kg^-1. The activity of ²¹⁰Po is higher in the surface soil (0-5 cm) and decreases as depth increases to 20 cm and remains nearly constant thereafter. The activity concentration is almost uniform in the grain sizes of 350-177 μm and below 177 μm. Pterobryopsis tumida (Hook.) Dix, a plant of the moss family, shows a very high level of ²¹⁰Po activity -- 2724±13 Bq kg^-1. Seasonal variation studies show elevated levels of ²¹⁰Po in vegetation during winter. The annual dry deposition rate of ²¹⁰Po was 53.4 Bq m^-2 yr^-1

[en] The establishment of baseline data on natural radiation background and understanding of distribution and basic dynamics of primordial radionuclides in the environment of Kaiga, where two nuclear power reactors of capacity 235 MWe each are coming up, would be of great importance to assess the degree of impact on the environment. Employing standard radiochemical methods and nuclear techniques concentrations of ²²⁶Ra,²¹⁰Pb,²¹⁰ Po and ²²⁸Ra were measured in soil samples of Kaiga environ. A gas flow type low background beta counting system was installed to carry out the counting of the beta activity. An ZnS(Ag) alpha counting system of efficiency 30% was used to measure alpha activity. Activity ratios were evaluated using the measured concentration of radionuclides. The concentration of²²⁶Ra was found to vary from 3.18 to 21.58 Bq/kg, and that of²²⁸Ra from 5.16 to 17.86 Bq/kg. It was interesting to find that the concentrations of these two radionuclides were almost equal in soil samples of Kaiga environ. Also the concentration of ²¹⁰Pb and ²¹⁰Po was found to be significantly high in these samples. Further, ²¹⁰Pb and ²²⁶Ra were found to be in disequilibrium. Implications of these findings are discussed and also compared with literature values reported for other environs. (author). 13 refs., 2 tabs

[en] Indoor and outdoor ²²²Rn concentrations, their diurnal variations and dependence on atmospheric pressure, humidity and temperature, rate of ²²²Rn exhalation from soil and ²²²Rn concentration in soil gas were studied in several places of Coastal Karnataka and Kaiga regions using an active monitoring system (Alphagurad). The indoor ²²²Rn concentration varied in 7-64 Bq m^-3 with a mean value of 32 Bq m^-3 and the outdoor concentration varied in the range 3-35.2 Bq m^-3 with a mean value of 15.7 Bq m^-3. The mean indoor and outdoor annual effective doses due to the inhalation ²²²Rn were 0.81 mSv and 0.099 mSv, respectively. Diurnal variation studies show that the concentrations are higher in the early morning hours and lower in the afternoon hours. The concentration increases with the increase of atmospheric pressure and humidity but decreases with the increase of temperature. The rate of ²²²Rn exhalation varied in the range 8.5-145.3 m Bq m^-2 with a mean of 61.7 m Bq m^-2 and ²²²Rn concentration in soil gas in the range 17.2–149.1 kBq m^-3 with a mean of 45.2 kBq m^-3. (author)

[en] Soil samples of Kaiga nuclear power plant environment were analysed for ²³⁸U, ²³²Th and ⁴⁰K activities by gamma spectrometry using a 90 cc HPGe spectrometer. Measurements were made to study spatial variation of activity as well as depth wise distribution up to 25 cm depth. The geometric mean value of activities of ²³⁸U, ²³²Th and ⁴⁰K were found to be 29.8 Bq/kg, 22.8 Bq/kg and 109 Bq/kg respectively. The depth profile studies reveal the increase of ²³⁸U and ⁴⁰K activities with depth while the activity of ²³²Th remain almost constant. The possible reasons for the observed trend of variation are discussed. The results are also compared with literature values reported for other environs. (author). 5 refs., 2 tabs

[en] In this work, a unique nanocomposite film based on poly (vinyl alcohol)/silver (PVA/Ag) has been synthesized using solution casting technique and the samples were exposed to gamma radiation for different doses 0, 25, 50 and 75 kGy. Ultraviolet-Visible spectroscopy, the characteristic Surface Plasmon Resonance (SPR) band placed at around 427 nm. FTIR analysis shows the formation of chemical bonding/conjugation between the Ag nanoparticles and PVA chains. X-ray diffraction analysis shows that Ag metal is present in face-centered cubic (FCC) crystal structure. The morphology of particles was studied using Field Emission Scanning Electron Microscopy (FESEM) it shows the nanoparticles are in spherical shape. The presence of Ag was confirmed using Energy Dispersive X-ray Spectroscopy (EDX) elemental analysis. Transmission Electron Microscopy (TEM) shows the particles were nano size and monodispersed. The antibacterial activities of the PVA/Ag nanocomposites were obtained using the zone inhibition method. The samples were tested against Gram-positive bacteria: Bacillus Subtilis, Staphylococcus aureus, and Gram-negative bacteria: Escherichia coli, Klebsiella pneumoniae. This study reveals that the irradiated PVA/Ag nanocomposites film shows good antibacterial activity against the Gram-positive and Gram-negative bacteria. (author)

[en] Investigations on the natural and artificial fallout radionuclides ²¹⁰Po and ¹³⁷Cs and the primordial radionuclide ⁴⁰K in the prominent tree species of Western Ghat tropical forests near Kaiga have been carried out as a part of baseline background radiation studies in the environment of Kaiga where nuclear power reactors are being installed. The prominent tree species of the region Tectona grandis L.f. and Terminalia paniculata Roth., and the commonly available epiphytic plant species Pterobryopsis tumida (Hook.) Dix. and Cymbidium aliofolium (Lo) Swartz. were chosen and concentrations of ⁴⁰K, ²¹⁰Po and ¹³⁷Cs were measured employing well-established nuclear techniques. The different parts of Cumbidium aloifolium (Lo) Swartz. such as leaves, stem, etc. were analysed to understand the absorption mechanism of fallout radionuclides. From a careful analysis of the results, the epiphytic plant species are identified as bioindicators to monitor fallout radionuclides. (Author)

[en] The ambient gamma radiation survey and thermoluminescent dosimetric studies conducted in the environment of Mangalore revealed significantly high gamma dose rates in certain locations of Ullal beach near Mangalore. Gamma spectrometric analyses of the soil and sand samples of this high background area have been carried out by employing a 133 cc Hp Ge detector coupled to a 4K MCA. Activities of prominent radionuclides of²³² Th series and those of ²³⁸U series were determined. The activity of²³² Th series was found to be significantly high. The activity ratios of daughter radionuclides of both ²³² Th and ²³⁸ U series were also determined. From the measured activity of²³² Th,²³⁸ U and ⁴⁰K the gamma dose rates were also evaluated. Results of these systematic investigations which establish the existence of monazite in Ullal beach near Mangalore are presented. (author). 7 refs., 2 tabs